Method of making injection molded footwear
A method of making injection molded footwear includes placing a last into the internal cavity of a mold with the last and cavity being configured such that there is a space between them which is greater than the desired thickness of the footwear skin. An elastically deformable scrim is placed over the last before the last is paced in the mold. The scrim has a first thickness when not compressed and a second thickness when compressed. The difference between the first and second thickness is approximately equal to the desired thickness of the footwear skin.
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BACKGROUND OF THE INVENTIONReferring to
The subject method of making injection-molded footwear comprises replacing the sock with an elastically deformable scrim having a first thickness when not compressed and a second thickness when substantially compressed, where the difference between the first and second thicknesses is approximately equal to the desired thickness of the upper skin of the resulting footwear.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.
The mold 16 and last 18 are similar to the mold and last of the prior art. Referring to
Referring now to
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
Claims
1. A method of making injection molded footwear with an upper skin having a predetermined thickness, comprising:
- a) providing a last;
- b) providing a mold having an internal cavity which is configured to receive said last with there being a space between said cavity and said last having a predetermined width which is greater than said predetermined thickness;
- c) placing a scrim over said last before said last is placed in said mold, said scrim being made from an elastically deformable material having a first thickness when not compressed and a second thickness when substantially compressed;
- d) the difference between said first and second thicknesses being approximately equal to said predetermined thickness; and
- e) infecting a fluid thermal plastic material between said mold and said last at a pressure between 300,000 and 400,000 pounds per square inch to compress said scrim to said second thickness.
2. The method of claim 1 wherein said first thickness is less than said predetermined width.
3. The method of claim 1 including the further step of after the injected thermal plastic material has cooled, removing said last from said scrim to allow said scrim to return to said first thickness.
4. The method of claim 1 wherein said predetermined thickness is between one millimeter and eight millimeters.
5. The method of claim 4 wherein said predetermined thickness is less than five millimeters.
6. The method of claim 1 wherein said first thickness is between two millimeters and nine millimeters.
7. The method of claim 6 wherein said first thickness is less than four millimeters.
8. The method of claim 7 wherein said second thickness is approximately one millimeter.
9. The method of claim 1 wherein said scrim is formed from a single layer of material.
10. The method of claim 1 wherein said scrim is made from multiple layers of material.
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Type: Grant
Filed: Mar 15, 2013
Date of Patent: Aug 23, 2016
Patent Publication Number: 20140259461
Assignee: Chinook Asia LLC (Lake Oswego, OR)
Inventor: Robert K. Scofield (Lake Oswego, OR)
Primary Examiner: Jill Heitbrink
Application Number: 13/838,382
International Classification: B29D 35/00 (20100101); B29D 35/12 (20100101);